Method for the chipless production of a rotationally symmetrical body from a circular sheet metal blank

Abstract

A method for chipless production of a rotationally symmetrical body from a circular sheet metal blank shapes the circular sheet metal blank into a pot-shaped body by pressing or pressure rolling around an inner mandrel, and a hub-shaped projection protruding outward from the base of the pot-shaped body is molded on by pressing around a central projection. The circular sheet metal blank is clamped only in the radial inner region of the blank in the axial direction between the inner mandrel and at least one projection during the shaping process.

Claims

1. A method for non-cutting production of a rotationally symmetrical body from a circular sheet metal blank, the method comprising: clamping the circular sheet metal blank in an axial direction only in a radial inner region of the circular sheet metal blank between an inner mandrel and an outer forepiece surrounding a central forepiece; in a first spinning process, forming the circular sheet metal blank into a pot-shaped preform only by spinning or flow-forming around the inner mandrel, wherein the circular sheet metal blank is held during the forming around the inner mandrel only by the outer forepiece; shaping the pot-shaped preform into a pot-shaped body by spinning or flow-forming around the inner mandrel; subsequently moving the central forepiece axially towards the inner mandrel to clamp the pot-shaped preform in a radially inner region of the pot-shaped preform against the inner mandrel by the central forepiece; moving the outer forepiece axially away from the inner mandrel and moving one or more spinning rollers radially inwards; and forming a hub-shaped projection protruding outward from a base of the pot-shaped body by spinning around the central forepiece.

2. The method according to claim 1, wherein the circular sheet metal blank is held only by the central forepiece and the inner mandrel during spinning around the central forepiece.

3. The method according to claim 2, wherein the pot-shaped preform is formed into a pot-shaped final form and thereafter the hub-shaped projection is formed on.

4. The method according to claim 2, wherein after the pot-shaped preform has been formed, the hub-shaped projection is formed on and thereafter the pot-shaped preform is formed into a pot-shaped final form.

5. The method according to claim 1, wherein the pot-shaped preform is formed into a pot-shaped final form and thereafter the hub-shaped projection is formed on.

6. The method according to claim 1, wherein after the pot-shaped preform has been formed, the hub-shaped projection is formed on, and thereafter the pot-shaped preform is formed into a pot-shaped final form.

7. The method according to claim 1, wherein before the pot-shaped preform is formed, the circular sheet metal blank is provided with a chamfered peripheral edge.

8. The method according to claim 1, wherein before the pot-shaped preform is formed, the circular sheet metal blank is provided with a central bore.

9. The method according to claim 1, wherein the circular sheet metal blank is preheated before and/or during spinning or flow-forming.

10. The method according to claim 1, wherein an inner mandrel having longitudinal grooves is used.

11. The method according to claim 1, wherein a central forepiece having a surface profiling is used.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) By way of example, the invention will be explained in more detail in the following on the basis of the drawing. Therein, respectively in a longitudinal section,

(2) FIG. 1 shows a circular sheet metal blank received in a pressing/shaping jig prior to the beginning of the shaping,

(3) FIG. 2 shows the reshaping of a circular sheet metal blank into a pot-shaped preform by pressing,

(4) FIG. 3 shows the reshaping of a circular sheet metal blank into a pot-shaped final form by pressure rolling, and

(5) FIG. 4 shows the molding-on of a hub-shaped projection by pressing.

(6) In the drawings, a pressing/shaping jig denoted in general by 1 is illustrated only with the elements essential for the invention. The pressing/forming jig 1 is configured in rotationally symmetrical manner around a longitudinal axis A and has a substantially cylindrical inner mandrel 2. A forepiece, which in the exemplary example is formed as in two parts, namely has a central forepiece 3 and an outer annular forepiece 4 surrounding the central forepiece 3, is disposed on the opposite side of the axial end 2a of the inner mandrel 2. Both the central forepiece 3 and the outer forepiece 4 are designed to be movable both ways in axial direction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(7) Furthermore, the pressing/shaping jig 1 has pressure rollers 5, 6 and 7, wherein several pressing rollers 5, 6, 7 may also be provided in a manner distributed over the circumference. The pressure rollers 5, 6, 7 are disposed in known manner opposite the forepieces 3 and 4 as well as the inner mandrel 2 such that they can rotate relative thereto, wherein the angular orientation and the geometric shape of the respectively desired pressure rollers 5, 6, 7 are adapted to the respective pressure-rolling process, i.e. to the desired shape and dimension of the rotationally symmetrical body to be produced.

(8) For implementation of the method according to the invention, a circular sheet metal blank 8 is clamped according to FIG. 1 between the outer forepiece 4 and the axial end 2a of the inner mandrel 2, by pressing the outer forepiece 4 in axial direction against the circular sheet metal blank 8 and thus the inner mandrel 2. Then the pressure roller 5 (or several pressure rollers 5) is set into rotational movement opposite the circular sheet metal blank 8 and thus the forepiece 4 and the inner mandrel 2, and at the same time the pressure roller 5 is moved in the direction of the arrow 9. Thereby a pot-shaped preform 10, which has an axially elongated region 10a on the outer circumference, is formed from the circular sheet metal blank 8. In the process, the circular sheet metal blank 8 is obviously held or clamped only in its radially inner region between the inner mandrel 2 and the outer forepiece 4.

(9) Thereafter the pot-shaped preform 10 is shaped with a second pressure roller 6 (or several pressure rollers 6) into a pot-shaped final form 11, by moving the pressure rollers 6 axially in the direction of the arrow 12 under simultaneous relative rotational movement opposite the outer forepiece 4 and the inner mandrel 2; this pot-shaped final form 11 has a substantially longer, axially elongated circumferential region 11a than does the pot-shaped preform 10.

(10) Thereafter the central forepiece 3 is moved axially in the direction of the arrow 13 toward the inner mandrel 2 and clamps the pot-shaped final form 11 in its radial inner region against the inner mandrel 2. Following this, the outer forepiece is moved axially outward in the direction of the arrow 13 and, in fact, so that that one or more pressure rollers 7 can be moved radially inward in the direction of the arrow 14. By simultaneous rotational movement of the pressure roll 7, a hub-shaped projection 16 is molded around the central forepiece 3 on the rotationally symmetrical body 17, which in this way becomes finished.

(11) Throughout the entire method workflow, the circular sheet metal blank 8 or the pot-shaped preform 10 obtained from it, the pot-shaped final form 11 and the end product, namely the rotationally symmetrical body 17, are held only in the radial inner region between the inner mandrel 2 and the central forepiece 3 or the outer forepiece 4.

(12) The method workflow may also be modified to the effect that the sequence of FIGS. 3 and 4 is inverted, i.e. that the after formation of the pot-shaped preform 10, the hub-shaped projection 16 molded on in the sense of FIG. 4 and then the pot-shaped final form 11 in the sense of FIG. 3.

(13) Instead of a flat circular sheet metal blank 8, a circular sheet metal blank equipped with a chamfered circumferential rim may also be used as starting product for the method workflow. Furthermore, prior to the pressing of the pot-shaped preform, the circular sheet metal blank may also be equipped with a central bore.

(14) Moreover, it may be provided that, prior to and/or during pressing or pressure rolling, the circular sheet metal blank 8 is preheated.

LIST OF REFERENCE SYMBOLS

(15) A Longitudinal axis 1 Pressing/shaping jig 2 Inner mandrel 2a Axial end 3 Central forepiece 4 Outer forepiece 5, 6, 7 Pressure rollers 8 Circular sheet metal blank 9 Arrow 10 Pot-shaped preform 10a Axially elongated region 11 Pot-shaped final form 11a Axially elongated region 12 Arrow 13 Arrow 14 Arrow 15 Arrow 16 Hub-shaped projection 17 Rotationally symmetrical body